Aircraft are provided with aircraft-wide systems for distributing power under normal operating conditions. The power is distributed from a range of power sources to each location on the aircraft where the power is required. The power is generally in the form of hydraulic, pneumatic or electrical power and is generated from onboard generators powered independently or by the aircraft's engines.
However, one problem with such aircraft-wide systems is that the cable or pipe runs are vulnerable to damage and require rigorous inspection and maintenance. Furthermore, the greater the physical distance between a generator and the site where its power is used, the greater the power losses in the pipe or cable-work. Also, longer pipe or cable runs increase the weight of the aircraft. In order to provide sufficient redundancy, multiple power systems are provided, further adding to the weight and complexity of the aircraft systems. In order to provide their power, each generator also either directly or indirectly consumes aircraft fuel.